The invention relates to a jacket for a floppy disk.
A floppy disk is rotatable, flexible disk coated with magnetizable material in a jacket. According to U.S. Pat. No. 4,414,597, a common, known jacket consists of a polyvinylchloride (hereinafter PVC) or another film exterior with an internal, nonwoven liner. The purposes of the film exterior are to provide the jacket with the stability and flexibility necessary for storage, handling, and use and to provide the magnetizably-coated disk with the necessary protection from mechanical damage from without. The main purposes of the liner are to gently pick up any dust particles on the magnetizable coating and to assure a low, uniform torque on the magnetizable disk in the jacket during rotational operation. The liner also prevents the magnetizable coating from coming directly into contact with the exterior film material which, in the case of PVC film, for example, could scratch it.
Floppy disk jackets with a PVC film exterior have a temperature stability of from about 10.degree. C. to about 70.degree. C. which is dictated by the thermal characteristics of PVC film. Difficulties from the temperature stability of such floppy disk jackets, for example from storage in motor vehicles, in sunny work areas behind glass, and on the cooling heat-transfer surfaces of office machines, have necessitated a search for new jacket materials which can replace the PVC.
Furthermore, the lack of porosity in PVC film can lead, undesirably, to condensation on the floppy disk under sufficient, cooling temperature conditions in the presence of moisture. Because putting perforations through the film has not brought reasonable relief, it has been necessary to seek suitable substitute materials for this reason as well.
It is also often desirable to write on the jacket of a floppy disk in use, for example to identify the material magnetically recorded thereon, or to imprint it before use, for example with advertising or other identification. Writing and imprinting media free of organic solvents, for example ordinary fiber-tip pen ink, ball-point pen ink, and pencil "lead", are not, therefore, suitable for writing on PVC film. As a result, pressure-sensitive labels are often placed on floppy disk jackets, but the ability to identify a disk jacket without using a pressure-sensitive label would considerably improve their handling. A substitute for a PVC cover is, therefore, desirable from this point of view, too.
In any case, however, the desirable dust and drag properties of the liner should be provided or preserved.
German patent publication No. 23 25 715 describes a protective envelope for a data medium stationary therein, and especially a video disk, having a cover of paper or an unspecified plastic with a liner of a nonwoven fiber coating. Such an envelope is temperature stable within wide limits. Also, the paper solves the problem of being able to write on or imprint the envelope. The envelope cannot, however, have all the specific mechanical properties required for protecting a flexible, rotating floppy disk such as tensile strength and scratch resistance, for example. Moreover, even when the nonwoven liner is laminated onto paper, the permeability of the nonwoven liner to moisture is so reduced by the paper that the envelope, in this regard, has virtually the same undesirable properties as the PVC film jacket cited above. This circumstance is not so very important if the envelope, as described in the patent publication, serves only for storing and handling the data medium and the latter is outside of the envelope during operation. This is not the case, however, for a floppy disk, which remains in its jacket and moves in it during use, and such a material is, therefore, unsuitable for it.
UK patent publication No. A 20 96 194 describes a sleeve of nonwoven fabric for a jacket for a phonograph record and it mentions the possibility of its use for a floppy disk. This sleeve has, however, the purpose of protecting the phonograph record or floppy disk in a jacket only during storage and handling, i.e., non-rotationally outside of the disk drive. The requirements for this are entirely different on account of the different type of application. The teaching of this patent is, therefore, not applicable to jackets which both envelop, i.e. jacket, and contact floppy disks.